This is some really old code that I wrote to work on the path problem (I didn't realize that I had never committed it.)  Anyway, you may find this interesting and as a possible way to augment your diff Gabe.  (Feel free to incorporate it).  I'll put a few comments in reviewboard here (which should probably just be in the code itself).

One major thing that should happen if you choose to use this is that path.py and maybe even SysPaths.py too should be in m5.util.